For example, Japanese Unexamined Patent Application Publication No. 2005-308124 discloses a technology for constituting an electromagnetic valve assembly by connecting a plurality of electromagnetic valves. In such an electromagnetic valve assembly, a stacking connector is attached to each electromagnetic valve, and stacking connectors of adjacent electromagnetic valves are connected to each other by a plug-in mechanism, so that electric signals such as serial signals, parallel signals, and electric power signals are transmitted and received between each of the electromagnetic valves.
As shown in FIG. 9, a publicly known stacking connector used for this kind of electromagnetic valve comprises a connector main body 1 including an insertion slot 3 and a plurality of socket terminals 4 for an electric connection, and a plug substrate 2 including a plurality of plug terminals 5 on both top and bottom surfaces thereof. An attachment side part 2a of the plug substrate 2 is inserted between ends of the socket terminals 4, and socket terminals 4 and plug terminals 5 corresponding to each other are bonded by solder 6, so that the connector main body 1 and the plug substrate 2 are connected to each other. Furthermore, an insertion side member 2b of the plug substrate 2 is inserted into an insertion slot of another stacking connector, so that the two stacking connectors are electrically connected to each other.
However, in the conventional stacking connector, when connecting the connector main body 1 and the plug substrate 2, the socket terminals 4 and the plug terminals 5 are bonded by the solder, and the solder 6 is used to secure the electric connection between both the terminals 4 and 5 and also to secure a mechanical bonding strength between the connector main body 1 and the plug substrate 2. Because of this, when the number of terminals is large, the soldering operation is cumbersome. Furthermore, when a detaching force is applied between the connector main body 1 and the plug substrate 2, and the force is directly applied to the socket terminals 4 and plug terminals 5, it is easy to cause solder flaking and damaged terminals.